This invention relates to any wheel driven vehicle or mobile equipment, more specifically to an improved method of controlling the differential or differentials of a vehicle.
To date limited-slip differentials, although having the benefits of increasing overall tractive effort of a vehicle in many conditions, primarily when one wheel contacts a surface with a lower coefficient of friction, also have some draw backs.
In the case of a standard limited-slip differential, when turning on dry pavement, while traction is not a concern, the friction that must be overcome between the clutch discs or the road surface and one or more of the vehicle wheels, causes strain and wear on drive-train components along with causing greater energy consumption required to overcome the friction.
In the case of a variable differential lock which uses the friction discs to create friction, the amount of locking force is not consistent due to the torque difference required to initially break the bond of the friction discs and the amount of torque required to maintain the slippage not to mention the associated wear to the friction discs.
The type of differential lock which uses the combination of friction discs that are compressed by the pumping action of an integral differential pump tend to give a “jerky” sensation when a wheel begins to spin and then locks. Other prior art using an integral pump with a fluid control device does not provide for any make-up or cooling fluid to automatically reenter the loop which makes them impractical.
All of these short comings of the prior art are overcome with closed-loop hydraulic adjustable slip differential. Component wear is minimized not eliminated, no high pressure rotating seals are used, the amount of “slip” can be tailored for conditions by operator or maximized when vehicle traction is not a concern there by requiring minimal power when turning.